1. Field of the Invention
The present invention relates to an electroacoustic transducer such as a sounder (buzzer), a microphone, or a loudspeaker, and more particularly to an improvement in which, in the case where an electroacoustic transducer is to be mounted on a board of one of various devices including a portable telephone, directionality in a circumferential direction (rotation direction) can be eliminated without using a sheet or a connector that may be separately prepared, thereby facilitating the mounting work.
2. Description of the Related Art
A sounder which is an electroacoustic transducer has a configuration such as shown in FIG. 21. The sounder has a case 301 which is configured by a top plate 303 and a cylindrical portion 305. Alternatively, the case 301 of the sounder may have a rectangular shape as shown in FIG. 23. A sound release hole 307 is formed in the center position of the top plate 303. A base 309 is placed in a lower portion of the inner space of the case 301, and a board 311 is placed on the side of the lower face of the base 309. A core 313 is attached to the center positions of the base 309 and the board 311. The base 309 and the core 313 constitute so-called xe2x80x9cpole piecexe2x80x9d.
A coil 315 is placed on the base 309 and wound around the outer periphery of the core 313. A magnet 317 is interposed between the outer periphery of the coil 315 and the cylindrical portion 305 of the case 301, with forming a gap between the magnet and the coil 315.
A stepped portion 319 is formed in an inner peripheral side of an upper end portion of the cylindrical portion 305 of the case 301. A diaphragm 321 is placed on the stepped portion 319. The diaphragm 321 is configured by an elastic plate 323, and a magnetic piece 325 which serves as an additional mass fixed to the center position of the elastic plate 323.
The ends of the coil 315 are passed through the base 309 and the board 311, and then connected to a pair of lead terminals (not shown) which are disposed on the lower face of the board 311.
The thus configured sounder operates in the following manner. The diaphragm 321 is ordinarily attracted to the magnet 317 to have a certain polarity. When a current is supplied to the coil 315 via the pair of lead terminals under this state, the core 313 is electromagnetized. As a result, a magnetic field is generated at the forward end of the core. At this time, in the case where the magnetic pole which is generated at the core 313 is different in polarity from that of the diaphragm 321, the diaphragm 321 is attracted to the core 313.
By contrast, when the magnetic pole of the core 313 is identical in polarity with that of the diaphragm 321, the diaphragm 321 is repelled from the core 313. When a current is intermittently supplied in a certain direction, therefore, the diaphragm 321 repeatedly conducts the above-mentioned operations, with the result that the diaphragm 321 is oscillated at a predetermined frequency to generate a sound.
The sounder configured as described above is mounted on a board 327 in a housing of, for example, a portable telephone. In the mounting of the sounder to the board 327, a sheet 329 is attached to the sounder to eliminate directionality in a circumferential direction. Specifically, as shown in FIG. 22, an anode conductive part 329a and a cathode conductive part 329b are disposed on the lower face of the sheet 329 in ring-like shapes which are concentric with each other.
A large number of conductive pins are formed on the sheet 329. The anode conductive part 329a and the cathode conductive part 329b are made conductive with the board 311 through the conductive pins.
When the sheet 329 is attached to the sounder, the sounder has no directionality in a circumferential direction with respect to an anode conductive part and a cathode conductive part of the board 327 of the portable telephone. Even when the sounder is mounted on the board 327 with being rotated or positioned at any degree in a circumferential direction, therefore, conduction between the sounder and the board 327 can be surely attained.
The anode conductive part and the cathode conductive part of the board 327 are placed in given radial positions corresponding to the anode conductive part 329a and the cathode conductive part 329b of the sheet 329.
In FIG. 21, the reference numeral 331 denotes a gasket serving as a cushion member. In the mounting of the sounder to the board 327 in the housing of the portable telephone, various electronic components including the sounder are clamped by the board 327 and the housing. Therefore, the gasket 331 is placed.
As a measure for eliminating directionality in mounting in a circumferential direction, it may be contemplated to dispose a predetermined connector on the board 327 of the portable telephone in place of attachment of the sheet 329 to the sounder.
The above-described configuration of the conventional art has the following problems.
A sounder of the conventional art is not configured so that directionality in mounting in a circumferential direction can be eliminated on the side of the sounder. Therefore, a measure such as that the sheet 329 which is separately prepared is attached, or that a connector is attached to the board 327 is required. This produces problems that extra components are necessary, and that a cumbersome work must be compulsively conducted.
Another problem is caused by the use of the sheet or the connector. A sounder is shipped with the acoustic performance previously adjusted. The acoustic performance may be changed by the sheet 329 or the connector which is thereafter attached to the sounder, thereby producing a problem that a sounder cannot provide desired acoustic performance.
Specifically, when the sheet 329 or the connector is disposed on the back face of the sounder, it is expected that the resonance space on the rear side of the diaphragm is closed or narrowed, whereby acoustic performance is changed. As a countermeasure against this, it may be contemplated that acoustic performance is adjusted and set previously in consideration of the sheet 329 or the connector. However, the sheet 329 or the connector is configured in various manners in accordance with requirements of the user. Therefore, it is practically impossible to previously specify the kind of the sheet 329 or the connector.
Such a problem is commonly applicable not only to a sounder but also to various kinds of electroacoustic transducers such as a microphone or a loudspeaker.
The invention has been conducted in view of these problems, and therefore an object of the invention is to provide an electroacoustic transducer and a structure for mounting an electroacoustic transducer on a board of an external device in which directionality in a circumferential direction in mounting can be eliminated without changing the acoustic performance.
To achieve the above object, according to a first aspect of the invention, there is provided an electroacoustic transducer to be mounted on a board of a device, comprising:
an anode conductive part which is in press contact with the board of the device; and
a cathode conductive part which is in press contact with the board of the device;
wherein said anode conductive part and said cathode conductive part are respectively placed at an axial center position or at predetermined positions in a radial direction to eliminate directionality in a circumferential direction.
According to a second aspect of the invention, in the electroacoustic transducer of the first aspect of the invention, said anode conductive part and said cathode conductive part are disposed in substantially ring-like shapes which are concentric with each other.
According to a third aspect of the invention, in the electroacoustic transducer of the first or second aspect of the invention, said anode conductive part and said cathode conductive part are projected toward said board, respectively.
According to a fourth aspect of the invention, in the electroacoustic transducer of the first or second aspect of the invention, at least one of said anode conductive part and said cathode conductive part is a coil spring or a plate spring.
According to a fifth aspect of the invention, in the electroacoustic transducer of the fourth aspect of the invention, said anode conductive part and said cathode conductive part are coil springs disposed concentrically, and a distance between the coil springs is larger toward a board of the device.
According to a sixth aspect of the invention, there is provided a structure for mounting an electroacoustic transducer on a device, comprising:
a pair of conductive parts of the electroacoustic transducer comprising an anode conductive part and a cathode conductive part;
a pair of conductive parts of the device comprising an anode conductive part and a cathode conductive part;
wherein at least one of the pairs of conductive parts is disposed in substantially ring-like shape with the anode conductive part is concentric with the cathode conductive part, thus eliminating directionality in a circumferential direction.
According to a seventh aspect of the invention, in the structure for mounting an electroacoustic transducer of the sixth aspect of the invention, one of the pairs is disposed in substantially ring-like shape and the other is disposed in predetermined positions in a radial direction corresponding to the position of said one of the pairs.
In the electroacoustic transducer of the first aspect of the invention, directionality in a circumferential direction is eliminated by respectively placing the anode conductive part and the cathode conductive part in predetermined positions including an axial center position in a radial direction. The electroacoustic transducer may be configured in various manners.
In the second aspect of the invention, for example, the directionality in a circumferential direction may be eliminated by disposing the anode conductive part and the cathode conductive part in substantially ring-like shapes which are concentric with each other. In this case, the anode conductive part and the cathode conductive part of a board of a device on which the electroacoustic transducer is to be mounted are not always required to be disposed in substantially ring-like shapes which are concentric with each other, and are requested only to be respectively disposed in predetermined positions in a radial direction.
In the third aspect of the invention, the electroacoustic transducer is configured so that, in the electroacoustic transducer of the first or second aspect of the invention, the anode conductive part and/or the cathode conductive part is configured by a coil spring or a plate spring. According to this configuration, a desired press contact force can be surely obtained, and a more sure contact state can be provided.
In the electroacoustic transducer of the fourth aspect of the invention, when both of the anode conductive part and the cathode conductive part are respectively shaped coil springs and disposed concentrically, the distance between the coil springs is larger toward the board of the device. According to this configuration, a contact between the anode conductive part and the cathode conductive part which may be caused by compression in mounting, and a short circuit caused by such a contact can be surely prevented from occurring.
In the structure for mounting an electroacoustic transducer of the fifth aspect of the invention, between an anode conductive part and a cathode conductive part of an electroacoustic transducer, and an anode conductive part and a cathode conductive part of one of various devices on which the electroacoustic transducer is to be mounted, the anode conductive part and the cathode conductive part, and/or the anode conductive part and the cathode conductive part are disposed in substantially ring-like shapes which are concentric with each other, thereby eliminating directionality in a circumferential direction. In this case, various combinations may be employed between the electroacoustic transducer and the board of the device.
In the sixth aspect of the invention, for example, a configuration may be employed in which one of a set of the anode conductive part and the cathode conductive part and a set of the board anode conductive part and the board cathode conductive part is disposed in substantially ring-like shapes which are concentric with each other, and another set is disposed in predetermined positions in a radial direction and corresponding to positions of the substantially ring-like shapes which are concentric with each other.